Comparison of the two assays in quantifying immune effector cell-mediated damage. Biofilms were seeded at 105 cells per 30 mm2 of well surface area and were incubated for 3 h or 48 h. HL-60 cells were subsequently added at two E:T ratios (10:1, dark bars; 1:1, light bars). Early or mature biofilm changes were quantified with the XTT (A) or qRT-PCR assays (B). % biofilm damage was calculated using changes in mean OD450 signals or mean EFB1 transcript copy numbers, in the presence or absence of effectors, as described in the text. Bars represent SD of triplicate HL-60 experiments. Student-t test p values are shown on the graph for each set of comparisons.